This invention relates generally to the field of infertility medicine and more specifically to a method and transfer catheter for use in assisted reproduction.
In assisted reproduction, reproductive material is introduced into a reproductive tract of a female. For example, the reproductive material may be embryos, gametes and zygotes. The reproductive material may be introduced transcervically to the uterus or fallopian tube using an appropriate transfer catheter and/or catheter system or introduced into the fallopian tube using laparoscopic techniques.
The insertion technique and/or the anatomy into which the transfer catheter is to be inserted impose size limitations on the catheter. This is particularly true for gamete intra-fallopian tube transfer (GIFT) procedures performed in a transvaginal route in which the internal diameter of the proximal portions of the fallopian tube (intramural and isthmic) can be as small as 0.75 millimeter. This imposes a significant constraint on the external cross sectional dimensions of the transfer catheter. In addition, the internal diameter of the transfer catheter should not be smaller than about 0.4 millimeter because forcing an embryo into a smaller lumen may be harmful to the embryo or detrimental to the process of loading or expelling the embryo from the transfer catheter.
With these small diameters, a transfer catheter can easily have its distal opening occluded when the catheter contacts soft tissues. When this occurs, a relatively high pressure is required to expel the reproductive material from the transfer catheter and this can result in a failed transfer or damage to the cells as a result of the high pressure applied to them through the transfer catheter.
One type of prior art transfer catheter has a distal opening lying in a plane which is perpendicular to the central axis of the catheter. This axially opening distal opening can be rather easily occluded.
Another type of prior art transfer catheter has a side opening rather than an axial opening. However, the side opening is also subject to occlusion when it comes into contact with tissue and this can happen, for example, because of the tortuous path defined by the fallopian tube. In addition, this type of transfer catheter is relatively difficult to manufacture and a large side opening proximal of the distal end would weaken the catheter and create a propensity to kink. Although other port arrangements are known for catheters used in other regions of the body, such as the vasculature, so far as I am aware none of them is .adapted for the deposition of reproductive material into the reproductive tract of a female.